Multigrid tube



W. STOF F MULTIGRID TUBE Filed July 21. 1933 Fig. 4 m veh'zoh Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE Application July 21, 1933, Serial No. 681,500 In Germany July 22, 1932 2 Claims.

The object of the invention is a multi-grid tube, which contains a protecting or screening grid and two control grids, one of which possesses a variable reciprocity.

According to the invention, the two control grids may be arranged either separately from each other along a single cathode, or in connection with separate cathodes.

Two forms of embodiment of the tube according to the invention are illustrated by way of example in Figs. 1-3.

Fig. 1 shows a multi-grid tube according to the invention, in which the two control grids are arranged along a single cathode whilst in Fig. 2 there is illustrated an arrangement having two cathodes.

Fig. 3 shows an arrangement according to Fig. 2 in plan.

In Fig. 4 there is illustrated a connection system for the tube according to the invention.

In the drawing I is the tube, having the exponential grid 3, an ordinary control grid 4, the screening grid 5, the control grid cooling surfaces 6 and the anodes I.

The control grids 3 and 4 may be arranged either along a cathode 2 (Fig. 1) or with the use of two cathodes (Figs. 2 and 3).

The tube according to the invention is suitable to a very large extent more particularly for heterodyne receivers. As shown in Fig. 4, the received frequency in this case may be conducted to the exponential grid, whilst the heterodyne frequency may be generated with the assistance of the grid 4.

By use of the tube according to the invention there is obtained a mixing arrangement, which also operates properly in the range of short and ultra-short waves, and possesses practically the maximum sensitivity which is capable of being obtained. By the use of a grid having a variable reciprocal of the amplification factor it is possible also in this stage to obtain an automatic regulation in the strength of sound, and thus to increase considerably the effect of the fading compensation in the complete arrangement.

I claim:

15 1. An electron valve comprising a cathode, a

control grid surrounding said cathode, a further cathode, a control grid the slope of which is different at different points, surrounding said further cathode, a screening grid surrounding said 20 elements and an anode arranged near said screening grid.

2. An electron valve comprising a screening grid and two control grids, one of which possesses a variable reciprocal of the amplification factor, 25 

